That looks bad, and it is, but it's better than some analysts predicted. VW could have been in deep negative territory, down close to 7% according to some predictions, so ending up with a flat September was modestly good news.

However, VW's US competition crushed it in September, as the German car maker struggled with a growing emissions-cheating scandal.

Toyota reported 16.2% growth. Ford was up 23%. Fiat Chrysler did 14%. The double-digit theme persisted throughout the automakers doing business in the US market.

Even the Labor Day weekend boost couldn't get VW into that club — although it probably mitigated some of the pain. September auto sales included the Labor Day weekend, which is one of the busiest periods times of the year for dealerships around the country.

Last year, Labor Day weekend was recorded in August sales data.

VW currently lacks a competitive compact or mid-size SUV to offer customers, and these are two of the hottest segments in the US. And that's starting to cause real problems. For the year, VW's US sales are down 2.46% compared to 2014.

The emissions-cheating scandal, which affects 11 million VW Group vehicles worldwide and about 500,000 in the US, hasn't yet had a chance to really hit VW sales, although it may have kept customers out of showrooms for the last week in September.

In any case, the scandal it's what the VW needed in the US, where it's goal of challenging General Motors an Toyota at the top of the market has largely failed. VW has less than 2% market share in the US, a situation that September's numbers won't improve.